定义自定义颜色Swift

Question

I'm rewriting my app in Swift (yes, hooray) and I'm running into the following:

I inherited a class, of which the definition is (.h)

#import <Foundation/Foundation.h>
#import <UIKit/UIKit.h>

@interface MWColor : NSObject

+ (UIColor *)gray;
+ (UIColor *)green;
+ (UIColor *)themeColor;


@end

In here, I define colors, that I can use throughout my project as such:

myView.backgroundColor = MWColor.gray()

Now, I want to do this in a proper Swift way.

What would be the best approach? Extensions?

Help me to be a good Swift citizen

Answer 1

You can add computed colours to UIColor in an extension like this...

extension UIColor {
    static var myRed: UIColor { 
        // define your color here
        return UIColor(...) 
    }
}

or even...

extension UIColor {
    static let myRed = UIColor(... define the color values here ...)
}

Then access it like...

let someColor: UIColor = .myRed

or

let otherColor = UIColor.myRed

This matches the way that standard colours are defined too..

UIColor.red
UIColor.yellow
UIColor.myRed

etc...

Answer 2

There are probably a thousand different ways to do this, but I use the following extension:

extension UIColor {

    convenience init(rgb: UInt) {
        self.init(
            red: CGFloat((rgb & 0xFF0000) >> 16) / 255.0,
            green: CGFloat((rgb & 0x00FF00) >> 8) / 255.0,
            blue: CGFloat(rgb & 0x0000FF) / 255.0,
            alpha: CGFloat(1.0)
        )
    }
}

Then you can set the color of any object using the common HEX color code of RGB colors. Quickly find HEX colors here: http://www.color-hex.com/

view.backgroundColor = UIColor(rgb: 0xFF0000) will set the backgroundColor of view to red.

Hope this helps